Liquid chromatography particle beam-mass spectrometry with massive cluster impact

A new liquid chromatography-mass spectrometry technique is described that utilizes a particle beam interface to transport and deposit desolvated analyte molecules onto a target surface that is bombarded by a primary beam of massive multiply charged glycerol cluster ions to generate secondary ions for mass analysis. The massive cluster ion beam is generated by electrohydrodynamic emission from a solution of 1. 5-M ammonium acetate in glycerol. In the present instrumental configuration the massive cluster ion gun is placed above the target probe and the particle beam interface is connected through a side port of the mass spectrometer. The massive cluster ion beam and particle beam are intercepted by a target surface substituted for a conventional ion volume. The target surface is positioned such that it is ～ 45 ° to the primary cluster ion beam, the particle beam, and the mass analyzer axis. This geometric orientation represents a compromise among the performances of these three elements. The feasibility of this liquid chromatography-particle beam on-line with massive cluster impact is demonstrated by flow injections of acetylcholine chloride and gramicidin S. Spectra generated from this preliminary study indicate promise for routine liquid chromatography-mass spectrometry of polar compounds by using a robust inlet and an effective generation of secondary ions without an added matrix.